Food habits, gastric digestion and food consumption rates of yellow perch, Perca fluviatilis flavescens (Mitchill), in West Blue Lake, Manitoba

Abstract

Food habits and rates of digestion and food consumption were determined for yellow perch in West Blue Lake, Manitoba during the spring and summer of 1969 and 1970. Perch were diurnal in both swimming and feeding activity. Composition and amount of food eaten by perch varied with time of day, season and size of fish. The greatest feeding activity generally occurred during mid-morning and early evening. Chaoborus sp pupae and cladocerans tended to be eaten in early morning and late evening while benthic organisms and fishes were eaten throughout the day. Seasonally, major components of the diet of adult perch were amphipods and immature aquatic insects in spring and early summer with fishes and crayfish predominating in late summer. For juvenile perch, cladocerans and amphipods were eaten in early and late summer with amphipods and fishes predominating in mid-summer. Weight of stomach contents increased with fish weight but not in a direct proportion. Cladocerans decreased in importance in the diet with increasing fish size while fishes and crayfish increased. Of the two species of amphipods in West Blue Lake, Gammarus lacustris tended to be eaten by adult perch while Hyalella azteca were eaten by juvenile perch... Amphipods formed the basic food item for perch in West Blue Lake, Cladocerans, immature dipterans, crayfish and fishes were of secondary importance while insects other than dipterans were of minor importance. Perch were classified as both secondary and tertiary consumers deriving approximately equal portions of their diet by weight from benthic and pelagic organisms (primary consumers) as well as from fishes (secondary consumers).